The three grades under this specification – namely, Grades PNS 230, 275, and 415 –trace their roots to ASTM specifications. And the terms ‘Structural’, ‘Intermediate’, and ‘High-tensile’ originated from earlier versions of ASTM-A615 but remained unchanged in deference to custom and familiarity among users. The table below provides a handy reference as to the common understanding in the market regarding these grades.

ASTM vs PNS Codes

Popular Nomenclature

Typical Application

Grade 33 / PNS 230

Structural Grade

Low-rise Buildings and Low Loading Conditions

Grade 40 / PNS 275

Intermediate Grade

Medium-rise Structures / Infrastructure Work

Grade 60 / PNS 415

High-Tensile Grade

Medium & High-rise Structures / Infrastructure

The three grades are distinguished by the different color markings painted at the ends of each bar, as shown in the following table:

It must be noted that, in the current PNS 49, rebars are further categorized into ‘weldable’ and ‘non-weldable’ grades. The difference between the two categories is primarily rooted in their different chemical compositions and carbon equivalents (CEQ). Despite the different nomenclatures and their connotations, both ‘Weldable’ and ‘Non-weldable’ grades can actually be welded. However, the relatively lower carbon content and CEQ of the so-called ‘weldable’ grade does make it easier to weld without having to worry about pre-heating and post-heating requirements and procedures, that is a concern highlighted especially in temperate situations.

For a plain round bar, determining its 'size' involves simply taking a direct physical measurement of its diameter since its circular cross section should remain quite uniform throughout its length. A plain round bar is considered to be dimensionally acceptable if its diameter, as measured, falls within the dimensional tolerances allowed by the Standard.

A rebar however is not measured in the same way as a plain round bar. Because of its non-uniform cross section, a rebar must comply with the allowable ‘Variation in Mass’ (VIM) in lieu of measurement of its diameter. Checking for this VIM involves taking and weighing one meter of rebar and comparing the findings against the standard value.

Because variation in cross sectional area occurs during hot rolling, a corresponding variation in linear weight is to be expected. For this reason, PNS-49 provides for an allowable ‘variation in mass’ (VIM) of ±6%, measured using one meter of rebar.